1. Field of the Invention
The present invention relates to an apparatus for processing a text and an image together and, more particularly, to a text/image processing apparatus for synthesizing a text and a document image.
2. Related Background Art
An arrangement of a conventional text/image processing apparatus will be described with reference to FIG. 2. The apparatus includes a host 200, an interface 220, a scanner 221, and a printer 222. A CPU 201 uses a RAM 203, an interrupt (INT.) controller 204, a timer/counter 205, and the like in accordance with firmware in a ROM 202 to control the overall operation of the apparatus.
A disc controller 217 controls a disc drive (not shown) and controls read/write access to a floppy disc (FD) 218 and a hard disc (HD) 219. 0S's, application programs, and data files composed of images and characters are stored in these discs. A keyboard (KB) 208 and a mouse 209 are connected to a CPU bus 223 through an I/O port 206. The I/O port 206 is also connected to external equipment indicated generally at 207. The I/O port 206 includes communication ports such as an RS232c and SCSi.
A CRT controller 211 displays contents of a display memory (VRAM) 213 on a CRT 210.
The scanner/printer interface (SCN/PRT IF) 220 fetches image information from the scanner 221 and sends out image data to the printer 222 in accordance with commands from the CPU 201. Image memories (IMEM1 and IMEM2) 232 and 233 are respectively bit map memories for storing image data read from the scanner and image data printed by the printer.
A text memory (TEXT MEM) 230 stores codes corresponding to characters of a text file (to be referred to as a text file) generated on the CRT by using the keyboard 208 and the mouse 209. A graphic memory (GMEM) 231 stores graphic information (to be referred to as a graphic file hereinafter) generated on the CRT.
Graphic information is stored as a bit image corresponding to a CRT display pixel or as vector information. The text and graphic files are normally stored in the floppy and hard discs 218 and 219. These files are called to the text memory 230 and the graphic memory 231 when they are edited on the CRT. The concept of synthesis of a text and a document image will be described with reference to FIGS. 2 and 3. A code-image converter 252 develops the text file in the text memory 230 into the VRAM 213 with reference to a font ROM 212. A graphic processor 251 transfers the bit image in the graphic memory 231 to the VRAM 213 by using a DMA controller 214 shown in FIG. 2. When the text file is stored as vector information, the graphic processor 251 vector-raster converts it into a bit image. The resultant bit image is developed in the VRAM 213. A natural image processor 250 reads out the size of the document image read by the scanner from the image memory 232 and reduces the size of the document image. The size-reduced document image is transferred to the VRAM 213. The converter 252 and the processors 250 and. 251 are controlled by the CPU 201 in FIG. 2. An exclusive (dedicated) CPU may be arranged to control the converter 252 and the processors 250 and 251 for high-speed processing, or the CRT controller 211 controls these components. A display information table 254 of image layout information representing portions of the text file and the graphic or image file in the VRAM 213 is stored in the RAM 203 in FIG. 2.
An operator edits the information displayed on the CRT with the keyboard 208 and the mouse 209. A synthesized image consisting of characters, figures, and images is edited on the CRT. During editing, the display information table 254 is continuously updated.
When a print request is input at the end of editing, the CPU 201 (FIG. 2) develops necessary information from the text memory 230, the graphic memory 231, and the image memory 232 in the image memory 233 as a bit image corresponding to a printer coordinate system. The developed information is output to the printer 222 through the scanner/printer interface (220 in FIG. 2), and the synthesized image consisting of characters, graphic patterns and the document image is printed. The image memory 233 may be a full-page memory for storing a one-page printing bit image or a partial buffer memory sufficient to cope with the developing speed of the image memory 233.
The natural image processor 250 extracts a desired portion of the document image information in the image memory 232 and performs various operations such as rotation, mirror image processing, and dark/bright reversing in addition to enlargement and reduction.
In the case of FIG. 3, the image memory 232 has a capacity of about 2 Mbytes so as to allow A4 size reading and printing at a resolution of 400 dots/inch.
The resolution of the CRT 210 is assumed to be 640 dots .times. 480 dots for monochromatic display, so that the VRAM 213 must have a capacity of 38 Kbytes.
The graphic memory 231 has a capacity of 38 Kbytes as a bit image memory.
The text memory 230 has a capacity of about 2 Kbytes when display of 40 digits and 25 lines is performed and a character code is given as 2-byte data.
At the time of development in the image memory 233, the contents of the VRAM 213 can be directly transferred from the CRT coordinate system to the printer coordinate system through a coordinates converter 253.
The feature of the conventional arrangement lies in the feature that a synthesized image of document image information and the text and graphic data is generated in the image memory 233 and is printed by the printer.
When the same arrangement as described above is designed incorporating a scanner and a printer which can input/output multivalue image information or full-color image information, the image memories 232 and 233 require a very large capacity. For example, in the case of a full-color image, if 8-bit R(red) data, 8-bit G (green) data, and 8-bit B (blue) data are used, A4 size at a resolution of 400 dots/inch requires a capacity of about 45 Mbytes, thus requiring an expensive memory. Even if such a large-capacity memory is available, a long time is required for handling of image data during editing. The response time on the CRT is undesirably prolonged and its operability is degraded.
In addition, since the volume of image data sent from the scanner is greatly increased, various problems are posed in transmission speed, transmission line capacity, and data fetching speed.
Image information may be compressed into codes, and the codes may be stored in the image memory. In this case, a data compressor and a data expander are required and the size of the electrical circuit and hence the cost are increased.
It is also possible to process all image data extracted in correspondence with the capacity of an image memory which can be mounted in the apparatus. In this case, performance of the scanner and the printer cannot be optimally utilized, and a high-quality synthesized output cannot be obtained.